This invention relates to a method of manufacturing a semiconductor device, which method comprises providing a semiconductor body having at a major surface a surface structure comprising an insulating layer through which is formed an opening defining a sidewall of insulating material bounding an exposed surface area of a region beneath the insulating layer, providing an activating layer on the exposed surface area and the sidewall of the opening, and depositing electrically conductive material to form an electrically conductive region in the opening in electrical contact with the underlying region.
U.S. Pat. No. 4,822,753 describes such a method. In the in U.S. Pat. No. 4,822,753, the opening in the insulating layer exposes a silicide surface area of a silicon device region and the activating layer is provided by blanket depositing a layer of titanium nitride over the insulating layer. A levelling or planarizing agent such as a spin-on-glass is then applied over the surface to fill the opening. The levelling agent is then etched anisotropically to leave the levelling agent only in the opening. The activating or nucleating layer is then etched using the levelling agent as a mask so as to remove the exposed areas of the activating layer. After removal of the remaining levelling agent, the titanium nitride activating layer provides a nucleation surface for the selective deposition of tungsten to form the electrically conductive material region or plug in electrical contact with the underlying region exposed by the opening.
In the method described in U.S. Pat. No. 4,822,753, the levelling agent acts as an etch mask to enable the portion of the activating layer in the surface of the insulating layer to be removed. However, the sidewall of the opening remains covered by the activating layer after removal of the remaining levelling agent. Accordingly, nucleation sites for the electrically conductive material are provided not only on the surface area to be contacted but also on the sidewall of the opening so that the electrically conductive material may be deposited on and thus `grow` from the sidewall as well as the surface area. Such sidewall growth of the electrically conductive material may result in voids or spaces in the electrically conductive region or plug which may detrimentally affect the quality of the electrical contact to the underlying region.